It was when John Freeman started receiving more than 200 emails a day that he thought things needed to change. As one of America's pre-eminent literary critics, Freeman's daily routine used to consist of going to a coffee shop in the morning to read and then returning home to write his reviews in the afternoon. But in his absence his inbox had swollen to unmanageable proportions.

"It quickly destroyed my attention span," Freeman says. "It was absurd. A friend visited from Kansas City, and we went to get a coffee. Forty-five minutes later, we came back to my apartment, and I logged on to my computer. It took about two minutes for email to download, marching down the screen like some sort of advancing army.

"I had received 72 messages in less than an hour. At that point, I just felt there was no way anyone can keep up with this biologically. It seemed shocking to me no one had written anything critical about where this sprawling messagopolis was going."

To plug the gap, Freeman wrote The Tyranny of Email, an eloquent polemic about the state of modern communication that has just been published in America.

According to Freeman, who is the new editor of Granta magazine and a former president of the National Book Critics Circle in the US, the modern tools of communication that are meant to connect us are actually driving us further apart. Instead of bringing us into closer contact with the global community, email, instant messaging, texting and social networking sites all enforce the notion of what the French philosopher Guy Debord termed "the lonely crowd".

Freeman argues that email encourages us to eschew face-to-face conversations with friends or colleagues in favour of the terse and anonymous immediacy of a computer-driven exchange.

And as the usage of digital communication has increased exponentially, our efficiency has paradoxically declined: we spend so much time checking our inboxes or refreshing our Twitter pages that, says Freeman, "our attention spans are fractured into a thousand tiny fragments".

We are, it seems, a society in the grip of information overload. Last year in the UK we spent 537% more time on Facebook than in 2007 and sent approximately 40 text messages a month. By 2011, it is estimated, there will be 3.2 billion email users worldwide.

According to Tom Stafford, a lecturer in psychology and cognitive science at Sheffield University, users of modern technology are often driven by the same gambler's instinct that motivates someone to play a slot machine.

"You never know when something is going to land in your inbox, so there is that tingle of excitement every time you check," says Stafford. "There's something about being in the process that's really immersive. We're engaged while it's happening. It looks like it is convenient, but it's not: you are distracted for the next half hour, asking yourself if someone has answered."

Researchers at Loughborough University found that it took an average of 64 seconds for a person to recover their train of thought after interruption by email: those who check their email every five minutes waste 8.5 hours a week in this way. "There is no doubt that people use it as an avoidance tactic," says Yoram Kalman, a post-doctoral researcher in online communication at the Open University of Israel. "The modern office worker works for an average of three minutes before an interruption occurs."

Kalman explains that, although we believe online and mobile technologies help us to get things done more efficiently, the mental impact lasts far longer than hitting the "send" button. Once we dispatch an email, a text or an instant message into the ether, our minds go through a series of semi-conscious calculations about how soon the recipient will get back to us. We exist in a state of heightened anxiety until they reply, yet we could have got the answer by picking up the telephone or walking down the corridor to ask them in person.

"Face-to-face communication has always been a little awkward," says Freeman. "How long do you hold eye contact? Where do you put your hands? Your breath might smell or you might have worn that sweater which makes your neck disappear. All this anxiety is erased over email, but along with it we lose quite a lot of the awareness that there is another person there. There's no body language or look of abject terror in someone's eyes to slow us down when we're about to blunder. So we type things we would never say in person."

The popularity of modern forms of communication has also led to a decline in more traditional ways of keeping in touch. A 2005 study by the Department for Education and Skills found that a third of girls aged 16 to 19 had never written a letter, with the figure rising to more than half among boys. The postal strikes bear testament to a mail service in decline: there has been a 10% annual fall in the number of letters and parcels delivered by Royal Mail, largely attributable to increased use of email. Compare this with the Victorian era, when letter writing was both a form of entertainment and a necessary means of keeping in touch – Henry James had more than 1,000 correspondents, while William Makepeace Thackeray wrote 15 letters every morning.

But there are less quantifiable effects. According to the psychiatrist Edward Hallowell, the stress of trying to process information as rapidly as it arrives is reducing us to quivering wrecks of indecision and demoralisation. As email becomes easier and quicker to use, we are finding it increasingly difficult to sift the relevant information.

Hallowell believes that the modern workplace, with its dependence on internet discussion forums and reply-to-all email circulars, induces an "attention deficit trait" that has been aggravated by the introduction of the BlackBerry, a gadget that ensures we now have continuous access to our inboxes and social networking feeds. In 2006 the Wall Street Journal coined the term "BlackBerry orphans" to denote the scores of children who felt neglected by their parents' obsessive compulsion to check their electronic messages.

"It's proved impossible to completely drop out of email contact," says Freeman. "It's become fundamentally embedded in just about every kind of work, especially journalism. I think people should use it less, and try thinking of attention as an ecology worth preserving in small acts like writing a letter or a postcard.

"The other big problem is that text is mutable. We might think we said what we meant, but there are so many ways to interpret language, and many forms of humour don't translate well into text alone. So a huge percentage of emails are misunderstood."

While our intentions can be misinterpreted without face-to-face contact, there is also the broader danger that our over-reliance on technologies will have a negative impact on language itself.

Naomi Baron, a linguistics professor at American University in Washington DC, argues in her book Always On that instant messaging, mobile phones and blogs are magnifying the casual "whatever" attitude towards formal writing among the younger generation.

Examination boards routinely report that "text speak" has crept into GCSE and A-level test papers. Whereas biographers or historians can draw upon a wealth of written archive material from previous centuries, there will be substantially less preserved for the future because so much of our cyberspace chatter is transient.

"By its very nature, email or text is not a convivial medium of communication," says Tom Hodgkinson, editor of the Idler magazine and author of How To Be Idle. "Something about it makes people communicate in an unsatisfactory way with bad grammar, bad spelling and bad punctuation, in mostly terse sentences. It makes you hurry."

Hodgkinson attempted to give up email two years ago, but his resolve only lasted a fortnight. "It was just impossible when I was trying to edit a magazine," he said, "but I have started writing my books first in longhand, with an ink pen, and then transferring it to a computer. I find that my thoughts flow much better that way.

"Offices used to be very noisy and full of clatter. Now everybody sits in their own horrible bubble on Facebook instead of actually talking to each other."

Still, it is not all bad. Freeman acknowledges that there are "enormous benefits" to modern forms of communication: "It's made all kinds of work more convenient… people have a desperate need to be in touch. I'm just arguing that it needn't always have to be at the speed that email travels."

But Yoram Kalman sounds a cautionary note against using technology as a scapegoat. "Usually, if you look behind the technology, you find culture, social behaviour and you find people," says Kalman. "Technology is neutral, it depends what you use it for."